Wang Yanming, Li Ming, Stadler Sonja, Correll Sarah, Li Pingxin, Wang Danchen, Hayama Ryo, Leonelli Lauriebeth, Han Hyunsil, Grigoryev Sergei A, Allis C David, Coonrod Scott A
Center for Gene Regulation, Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA.
J Cell Biol. 2009 Jan 26;184(2):205-13. doi: 10.1083/jcb.200806072. Epub 2009 Jan 19.
Peripheral blood neutrophils form highly decondensed chromatin structures, termed neutrophil extracellular traps (NETs), that have been implicated in innate immune response to bacterial infection. Neutrophils express high levels of peptidylarginine deiminase 4 (PAD4), which catalyzes histone citrullination. However, whether PAD4 or histone citrullination plays a role in chromatin structure in neutrophils is unclear. In this study, we show that the hypercitrullination of histones by PAD4 mediates chromatin decondensation. Histone hypercitrullination is detected on highly decondensed chromatin in HL-60 granulocytes and blood neutrophils. The inhibition of PAD4 decreases histone hypercitrullination and the formation of NET-like structures, whereas PAD4 treatment of HL-60 cells facilitates these processes. The loss of heterochromatin and multilobular nuclear structures is detected in HL-60 granulocytes after PAD4 activation. Importantly, citrullination of biochemically defined avian nucleosome arrays inhibits their compaction by the linker histone H5 to form higher order chromatin structures. Together, these results suggest that histone hypercitrullination has important functions in chromatin decondensation in granulocytes/neutrophils.
外周血中性粒细胞形成高度解聚的染色质结构，称为中性粒细胞胞外诱捕网（NETs），其与针对细菌感染的固有免疫反应有关。中性粒细胞表达高水平的肽基精氨酸脱亚氨酶4（PAD4），该酶催化组蛋白瓜氨酸化。然而，尚不清楚PAD4或组蛋白瓜氨酸化是否在中性粒细胞的染色质结构中发挥作用。在本研究中，我们表明PAD4介导的组蛋白高度瓜氨酸化可介导染色质解聚。在HL-60粒细胞和血液中性粒细胞的高度解聚染色质上检测到组蛋白高度瓜氨酸化。抑制PAD4可减少组蛋白高度瓜氨酸化和类NET结构的形成，而用PAD4处理HL-60细胞则促进这些过程。在PAD4激活后，HL-60粒细胞中检测到异染色质和多叶核结构的丧失。重要的是，对生化定义的禽核小体阵列进行瓜氨酸化会抑制其通过连接组蛋白H5压缩形成更高阶染色质结构。总之，这些结果表明组蛋白高度瓜氨酸化在粒细胞/中性粒细胞的染色质解聚中具有重要功能。
